The Southern Song Dynasty, founded in 1127, was toppled in 1279. Prior to this change, the Mongol Khan Kublai altered the title of his reign to "Dayuan" and claimed himself the founding emperor of the Yuan. The Yuan Dynasty (1271-1368) emerged as the first national political power characterized by minority rule of China.

Tibet was officially incorporated into China during the Yuan Dynasty, a historical fact that neither Xagabba nor Van Praag can deny. Undaunted, however, the two concoct the "Cho-yon relationship" between the Chinese emperor and the Tibetan lamas, stating that this was the only type of relationship in existence at the time.

"Cho-yon" is a Buddhist word meaning patron. The "Cho-yon relationship" is also called "the relationship between the patrons and the lamas." The rich, who believed in Buddhism, often offered alms to monasteries and eminent monks. In return, they enjoyed priority in having the monks to recite Buddhist scriptures on their behalf. The relationship was fixed as the "Cho-yon relationship." Such a situation is widely found in the Buddhist world.

During the Yuan Dynasty, the emperor did offer alms in terms of gold and materials to major lamas of the Sagya Sect of Tibetan Buddhism. For example, twice in two years Kublai Khan, the founding emperor of the Yuan Dynasty, offered large amounts of gold and materials as alms to Pagba, the Prince of Dharma of the Sagya Sect in Tibet. The first offering was composed of kasaya adorned with gold and pearls, long sleeveless jackets, jewel-encrusted utensils, Buddhist robes, hats, boots and cushions, plus one large gold ingot, four large silver ingots, riding beasts, mules and golden saddles. The second offer was composed of 56 large silver ingots, 200 bags of tea and 110 bolts of brocade. Also, in 1277, when Pagba held a Grand Summons Ceremony in Tibet that was reportedly attended by some 70,000 monks, the crown prince of Kublai Khan granted each participating monk one qian (equal to five grams) of gold. Reciprocally, Pagba promised to satisfy the demands of the emperor and members of the imperial family for religious activities. Pagba three times conducted Abhiseka consecration and other rituals for Kublai Khan. These historical facts point to the fact that the "Cho-yon relationship" did exist between the Yuan emperor and the Prince of Dharma of the Sagya Sect in Tibet. The question, however, is whether the "Cho-yon relationship" was the principal or even the only relationship that existed at the time between the two.

Historical facts suggest that, in addition to the "Cho-yon relationship" between the Yuan emperor and the Prince of Dharma of the Sagya Sect of Tibetan Buddhism, a political relationship of superior and subordinate also existed, i.e., a relationship between sovereign and subject. This political tie would have been much more important than the "Cho-yon relationship."